[rollei_list] Re: OT Ancient Computers (was Re: Re: Rollei -Singapore) now analogue versus digital

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Mon, 12 Jan 2009 14:26:20 -0800

----- Original Message ----- From: "Frank Dernie" <Frank.Dernie@xxxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, January 12, 2009 7:38 AM
Subject: [rollei_list] Re: OT Ancient Computers (was Re: Re: Rollei -Singapore) now analogue versus digital

The fact that several (no more) prominent people still use film is not evidence that it is better. In all practical ways digital has exceeded the capability of film for some time. Certainly if there is an effect which one wishes to achieve, using a vintage LF lens for example, film may have to be the choice but that does not make film better, just an appropriate choice in some circumstances. Analogue sound is the same. The fact that some people prefer the sound of analogue is not evidence that it is better (I am one by the way) but that it matches their taste in sound. My Mum likes her old valve (tube) radio - "lovely tone" and it does sound nice, but there are no high frequencies at all, along the same lines as LPs in real world systems but more extreme. When Meridian, the digital specialists, were looking at the frequency and amplitude of the "music data" on LP records the -highest- dynamic range they found was equivalent to 11-bit IIRC, though many "experts" attribute the inferiority of digital as they hear it to the inadequacy of 16 bit recording, which it almost certainly can't be. The shortcoming of the 44.1kHz sampling frequency is a different story in real engineering implementation though. I designed high end HiFi equipment for a while. I have never seen so many ridiculous pseudo-technological explanations for real phenomena in any other field of work I have done.

In the long ago I did a lot of custom recording. At the time we used mostly 15 IPS tape, mostly on Studer machines with Dolby A. As a back-up we began to use a Sony digital adaptor running on a VTR. This was an early device and had problems but worked pretty well. The general opinion was that the digital recordings sounded "harsh" compared to the tape. However, what I found was that digital sounded more like what I heard in the monitors during recording, the harshness came from the microphones being used and their positions. Both mics and techniques had evolved to overcome the mushiness of tape. Disc recoding has a set of vices all its own. Among them are some inherent distortions which are very hard to reduce plus the fact that the "scanning" errors become worse toward the inside grooves due to the reduced goove velocity. Oval rather than round needles help reduce scanning errors at all speeds but still can not completely overcome the odd order harmonic distortion of the system. Typical disc systems have harmonic distortion on the order of a few percent and can have lots of intermodulation distortion. Analogue tape recording using biased direct recording has other types of distortion plus the lateral print effect that causes loss of high frequencies over time, especially the first few hours after a recording has been made. Digital has none of these plus it has absolute timing, meaning no flutter or wow. The greatest problem with digital as it is practiced is that the sampling frequency was chosen to accomodate the bandwidth limits of what is now very old analogue recording technology. The problem comes not from the sampling frequency itself but rather the anti-aliasing filters. Because the sampling rate is close to the Nyquist minimum the filters must of necessity be very sharp which can cause all sorts of problems with phase shifts and ringing. Raising the sampling frequency would probably eliminate this completely.

Richard Knoppow
Los Angeles, CA, USA
Rollei List

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